A fracture with no pressure gradient along the fracture plane during the flow.
It's a proxy concept as the continuous flow along fracture can not happen without pressure gradient at all.
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It happens because permeability of the fracture is usually much higher than that of reservoir and the fluid flow velocity along the fracture plane is much higher than in reservoir and corresponding pressure gradient is much lower than in reservoir.
In Pressure Transient Analysis the infinite conductivity fracture is the most popular practical case.
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